Twitter is a linguistic marketplace (Bourdieu, 1977) in which the processes of self-branding and micro-celebrity (Marwick, 2010) depend on visibility as a means of increasing social and economic gain. Hashtags are a potent resource within this system for promoting the visibility of a Twitter update (and, by implication, the update’s author). This study analyses the frequency, types and grammatical context of hashtags which occurred in a dataset of approximately 92,000 tweets, taken from 100 publically available Twitter accounts, comparing the discourse styles of corporations, celebrity practitioners and ‘ordinary’ Twitter members. The results suggest that practices of self-branding and micro-celebrity operate on a continuum which reflects and reinforces the social and economic hierarchies which exist in offline contexts. Despite claims that hashtags are ‘conversational’, this study suggests that participatory culture in Twitter is not evenly distributed, and that the discourse of celebrity practitioners and corporations exhibits the synthetic personalization (Fairclough, 1989) typical of mainstream media forms of broadcast talk.